Clinical observations on a newly designed electronic apex locator

The introduction of alternative electronic principles and circuitry has produced the next generation of electronic apex locators, which have fewer clinical limitations and greater ease of use, on a routine basis, than their predecessors. The history of how the electronic apex locator was developed over the past 30 years and the limitations of the machines designed on earlier principles are reviewed. Clinical examples of root canal systems measured using a newly-designed, frequency-dependent apex locator are presented in order to illustrate the spectrum of cases that can be read. All measurements were made on canals irrigated previously with electro-conducting solutions, which would have made readings from earlier machines problematic. Single-rooted and molar teeth as well as teeth with vital tissue in the root canal system or with necrotic pulp tissue and periapical lesions have been treated with equal ease and results. The electronic apex locator is being advocated to supplement instrumentation technique and to improve the identification of the apical terminus of the root canal system. The routine use of these devices is advocated to ensure an accurate placement of root canal fillings rather than to eliminate the need for radiographs.